Aiken was born in Mermaid Street in
Rye, Sussex, on 4 September 1924. Her father was the American
Pulitzer Prize-winning poet
Conrad Aiken (1889–1973). Her older brother was the writer and research chemist John Aiken (1913–1990), and her older sister was the writer
Jane Aiken Hodge (1917–2009). Their mother, Canadian-born Jessie MacDonald (1889–1970), was a Master's graduate from
Radcliffe College,
Cambridge, Massachusetts. Jessie and Conrad's marriage was dissolved in 1929, and Jessie married the English writer
Martin Armstrong in 1930. Conrad Aiken went on to marry twice more. Together with her brother John and her sister Jane, Joan Aiken wrote
Conrad Aiken Remembered (1989), a short appreciation of their father. Aiken was taught at home by her mother until the age of twelve and from 1936 to 1940 at
Wychwood School for girls in
North Oxford. She did not attend university. Writing stories from an early age, she finished her first full-length novel when she was sixteen and had her first short story for adults accepted for publication when she was seventeen. In 1941 her first children's story was broadcast on the
BBC's ''
Children's Hour''. Aiken worked for the
United Nations Information Centre (UNIC) in London between 1943 and 1949. In September 1945 she married Ronald George Brown, a journalist who was also working at UNIC. They had two children before he died in 1955. After her husband's death, Aiken joined the magazine
Argosy, where she worked in various editorial capacities and, she later said, learned her trade as a writer. The magazine was one of many in which she published short stories between 1955 and 1960. During this time she also published her first two collections of children's stories and began work on a children's novel, initially titled
Bonnie Green, which was later published in 1962 as
The Wolves of Willoughby Chase. By then she was able to write full-time from home, producing two or three books a year for the rest of her life, mainly children's books and thrillers, as well as many articles, introductions and talks on children's literature and on the work of
Jane Austen. In 1976 Aiken married the
New York landscape painter and teacher Julius Goldstein (died 2001). They divided their time between her home (the Hermitage in
Petworth, Sussex) and his native New York. In September 1999, she was made a
Member of the Order of the British Empire. Aiken died at home at the age of 79 in 2004. She was survived by her two children. == Writings ==